There are three Flowers scattered around the area and they are all marked on the map. In order to make a flower bloom the Fateless One needs to attack it with a fire weapon (or spell) and then use the Pertichor on it.

Once all three have bloomed, return to Calovar for your reward (level-based XP ~370 at level 30, but no Gold).

A commonly-reported bug occurs when the player reaches one of the Century plants, uses fire on it and is then prompted to hit the activate button or key ("F" on a keyboard). The game crashes to the desktop as soon as the key/button is used. On the PS3, the game will freeze and the system will need rebooting. This also occurs on XBox 360, if you've completed the Bloodbane quest before getting this one and had accidentally hit the Century plant with fire.